Heavy Gitlab CI user here. The real problem is isolating the runners themselves. You can assign runners to individual projects for isolation, but when the runne

Heavy Gitlab CI user here. The real problem is isolating the runners themselves. You can assign runners to individual projects for isolation, but when the runners can't be AWSed (iOS hardware, for example) you have to make tough choices about buying more stuff to sit under your desk right next to the stuff you could be using that's idle. IMO some basic isolation measures like clearing the cache between projects would be good. Killing active processes when a job ends.